Re: MIDI playback lacks polyphony

[Keith E OHara]

On Thu, 21 Oct 2010 08:42:09 -0700, Jan wrote:

> 2010/10/21 Javier Ruiz-Alma
> >  Hello Dear Gurus,
> >   Lilypond is correctly engraving this score in .pdf, which has some
> > sections of single-staff polyphony.  However, the MIDI playback on my PC
> > plays one voice only.  I'm ignorant to where the problem is.   Is
> > my lilypond syntax incorrect?  Is my PC (Win7/WMP10) not able to play
> > multivoice MIDI? Is lilypond not adding the 2nd voice to the MIDI file?
> > Thank You, Javier
> Looks like only the notes that are "repeated" are
> lost (i.e. in measure 4 there is still ees2 from lower voice sounding while
> ees8 in upper voice appears, and this ees from upper voice is missing).

There is a lot of stuff going on in your example, Javier, but it looks like Jan 
narrowed it down to the thing that was bothering you.

Lilypond chooses to omit repeated notes from the MIDI file, if the earlier note 
in the same MIDI channel and if the earlier note would continue sounding 
through the new note.  (Arguably, this is not the very best thing for Lilypond 
to do.  If I put the repeated notes in by hand-editing the .midi file, they 
happen to play on windows media player, but I've heard people argue about 
whether such notes are legal MIDI.)

If you have several voices on each staff, but less than 16 voices total, then you 
probably want to use the method in the Snippet: "Changing MIDI output to one channel 
per voice"

\score {
 \new Staff  \relative c''
 << <c e g>1   {c,8 e g c e g c e} >>
 \layout{}
 %\midi {}
 \midi {
   \context {
     \Staff
     \remove "Staff_performer"
   }
   \context {
     \Voice
     \consists "Staff_performer"
   }
 }
}